1. Field of Invention
The present invention relates to a UPS (Uninterruptible Power System) server, and more particularly relates to a power system for a UPS server.
2. Description of Related Art
UPS (Uninterruptible Power System) is a constant voltage and constant frequency AC power supply, which includes an energy storage device and mainly consists of a rectifier and an inverter. The UPS provides an uninterrupted power supply by mainly using an energy storage device such as a battery for a computer, a communication network system or an industrial control system like a computer/server, a storage device, a network equipment and industrial equipment that requires continuous operation. For example, when city power is inputted normally, the UPS first stabilizes the city power and then provides for a load. Herein, the UPS is equivalent to an AC power stabilizer, and meanwhile the UPS charges an energy storage device (such as a battery cell). When the city power is interrupted, the UPS instantly provides the electrical energy stored in the energy storage device to the load by inversion conversion so as to continuously supply the AC power to keep the load working normally and to protect software and hardware of the load from being damaged.
For a UPS server, its output power source generally is a low-voltage, high-current DC power source, and thus the design of the power system in the UPS server is crucial. Specifically, factors of the power system including UPS efficiency, an input power factor, an input resonant current content and inversion and bypass switching time are important performance parameters. It is quite a common solution employed in the prior art to input a 380V three-phase AC voltage to a high-voltage power supply which is formed from an AC/DC converter and an isolated DC/DC converter connected in series. Firstly, the AC/DC converter converts a 380V AC voltage to a DC voltage, and the DC voltage is stepped down to generate a low DC voltage. After a DC PDU (Power Distribution Unit) is adopted to make a reasonable distribution, the required DC power voltage is obtained.
In another solution, the 380V three-phase AC voltage is distributed by an AC PDU in a reasonable way to obtain a 220V single-phase AC voltage. Then, the single-phase AC voltage is inputted to a server power supply which is formed from a low-voltage AC/DC converter and an isolating DC/DC converter connected in series. However, it is revealed from the above two solutions that the current UPS can only accept an AC input manner and the battery for storing power has to meet the requirement of large capacity (e.g. 240VDC). Furthermore, the current UPS needs several steps of conversion from AC to DC and from DC to DC, which inevitably reduce the efficiency of the UPS and further influence the performance of the UPS.
In view of the above, it is a problem desired to be solved by this industry regarding how to design an efficient power system for the UPS server, so as to eliminate or reduce the deficiencies or defects mentioned above.